The invention refers to the protection of piping systems containing water from damages due to freezing.
During vacation time in winter or in holiday resorts there is a necessity to protect the domestic water installation and also the hydronic heating system from freezing. Known are heating cables, which are in heat conducting contact with the pipes, however, it is difficult or even impossible to apply it to existing installations. Usually the hydronic heating is kept working at a reduced temperature, which means unnecessary energy consumption. It is also possible to fill the hydronic system with a mixture of water and the expensive glycol, which requires a higher velocity of flow within the pipes than with water.
The invention shows a way to avoid these disadvantages. The invention takes advantage of the fact that the surface of the pipes is much smaller than the surface of the radiators and that in the beginning only such pipe sections tend to freeze, which are exposed to draft, while the water in all other pipes and especially in the hot water tank still has a temperature above the freezing point. According to the invention a connecting pipe with a circulator pump is arranged at the end of the distribution lines between the hot water pipes and the cold water pipes, whereby the circulator pump is switched on by a thermostat as soon as the room temperature falls below a preset temperature, for instance 4xc2x0 C. In domestic hot water systems with a storage tank the water temperature stays above the freezing point for several days. For longer periods of cold weather and also for installations without a tank, a resistance heater, which forms a unit with the circulator pump, will be provided. In installations with a hot water recirculation pump no additional pump will be needed. If a circulator pump conveys the cooled down water through a circulation pipe back into the hot water tank, a connection with a valve between the outlet port of the pump and the cold water line is necessary which prevents that cold water flows into the hot water system. In installations in which the cooled down content of the hot water pipes is conveyed back into the cold water pipe, only a room-thermostat will be necessary which turns on the pump as soon as the room temperature falls below for instance 4xc2x0 C. (39.2xc2x0 F). In installations with a microprocessor, the program of the processor will activate the pump in case of freezing danger.
The invention can not only be used in domestic hot water systems but also in hydronic heating systems. In this case the heating circulator can be used. As soon as the room temperature falls below for instance 4xc2x0 C., a thermo-switch activates the circulator pump once or twice per hour for as long as it takes to circulate the whole content of the water in the heating circuits approximately two times. As soon as the water temperature falls below 2xc2x0 C., a second thermostat activates a heating element for instance a heating wire wound around one of the pipes and sets the pump to run continuously. Also in hydronic systems a resistance heater of low performance is advantageous.